In the drilling and completion industry, the formation of boreholes for the purpose of production or injection of fluid is common. The boreholes are used for exploration or extraction of natural resources such as hydrocarbons, oil, gas, water, and alternatively for CO2 sequestration. A completion system for producing natural resources from the borehole typically includes production tubing to deliver the natural resources from a reservoir to a surface location where the natural resources can then be harvested, collected, or processed. As natural resources flow through a perforation cavity or through a horizontal borehole, the pressure in the production tubing is less than the pressure in the formation. The greater the difference between the two pressures, the higher the flow rate. This differential pressure that drives the natural resources from the formation into the production tubing is called the drawdown pressure.
Chemical injection systems for injecting chemical fluids into the production tubing include a chemical injection line that extends to the surface where the borehole is drilled. Chemicals, such as demulsifiers, clarifiers, corrosion inhibitors, scale inhibitors, dewaxers, and surfactants can be pumped downhole into the production tubing via the chemical injection line for assisting in the production process. The chemical injection line can be connected to a chemical injection valve at the production tubing for controlling flow between the chemical injection line and the production tubing. Chemical injection valves include check valves to block unwanted fluids from entry therein by preventing fluid from the production tubing from entering the chemical injection lines. The chemical injection valve also includes a main spring which must be overcome by a certain opening pressure to prevent the chemical inside the chemical injection line from flowing freely into the production tubing or borehole until the pressure within the chemical injection line during chemical delivery is sufficient to open the valve. Current technology for chemical injection valves employ main springs capable of supporting up to 4,000 psi of hydrostatic pressure.
The art would be receptive to downhole systems having chemical injection valves capable of dealing with varying pressures, and methods for compensating for downhole pressures.